This invention relates to a volumetric modular building system.
Volumetric modular building systems are well known methods of construction which utilize the benefits of industrialization, prefabrication and standardization in the structural form of component modules and also incorporate a substantial amount of finished works into their production before transport and erection on site.
The design size of each habitable volumetric module is determined by eventual use and also by handling, transporting and lifting considerations. Moreover the design of structural connections and the geometry of horizontal and vertical joints between such modules are both governed by tolerances that can be achieved for the dimensions of individual modules.
Special arrangements for handling, lifting or transporting volumetric modules may be required if they are too heavy or over-size for normal road, rail or sea transport thus preventing their use due to excessive cost.
The use of slender sections or lightweight materials in order to overcome module size or weight restrictions may, for example, cause stress concentrations leading to long- term structural weakness, or perhaps involve excessive production or maintenance costs.
According to the present invention there is provided a volumetric modular building system comprising a reinforced concrete inverted xe2x80x98tee-beamxe2x80x99 module having a series of integral cross-walls which are spaced to coincide with the dimensions of the rooms and corridors constituting a section of a building, these rooms being formed by a matched pair of such modules acting in parallel, separated by, and adapted to support between them, a suspended concrete floor, external infill walls, internal partition walls, fixtures and services. There may preferably be provision for any number of matched pairs stacked side by side, end on end or one upon another producing buildings from one to ten stories in height under a single roof.
The dimensional control of reinforced concrete inverted xe2x80x98tee-beamxe2x80x99 modules is ensured by means of a removable structural steel framework gauge attached to, and forming part of the casting mold adjacent to the ends of the integral cross-walls described above. The legs of the gauge serve to locate, and secure during casting, top and bottom steel bearing-plates which are in turn separated, regulated and perforated by vertical steel tube tie-rod sleeves embedded locally near the ends of the concrete cross-walls.
The xe2x80x98primaryxe2x80x99 legs of the gauge, being attached to xe2x80x98primaryxe2x80x99 crosswalls, provide the means by which modules are fastened and secured for safe handling and transport, and also during the sequence of lifting, positioning and fixing operations at the site. To achieve standardization in length within the range of module sizes and in order to ensure simplicity and economy of the handling and installation operations, the spacing in plan, between the outside faces of primary gauge legs is prescribed to be the same as the overall length of a standard ISO Series 1 freight container.
The xe2x80x98primaryxe2x80x99 gauge leg xe2x80x98corner structurexe2x80x99 is designed in accordance with ISO specifications for such containers and the attachment, by welding, to xe2x80x98corner fittingsxe2x80x99 in accordance with ISO 1161(BS3951:Part1:1985) and the relevant ISO standards for testing such containers. This is in order to facilitate top xe2x80x98twist-lockxe2x80x99 loading and the transfer and fastening of the modules onto skeleton trailers and flat-bed railcars, or for handling and stacking of modules either at the fabrication plant, the dockside or within container ships.
Module width is confined between the extremities of installed gauge legs also being prescribed as that for standard ISO containers, namely 8 ft 0 ins. (2438 mm.)
Module height , being fractionally shorter than the height of gauge legs, is preferably the same as, but not limited to that as for Series 1AA or 1CC ISO freight containers having a nominal height of 8 ft 6 ins. (2591 mm.).
Similar gauge legs are fixed at the ends of other crosswalls prior to concrete casting, however, these xe2x80x98secondaryxe2x80x99 gauge legs have plain ends without corner fittings. They can be used as fenders whilst modules are in transit, but since they are not used for lifting purposes they can be disconnected before each module is installed. The exposed parts of the embedded fixings can be used to support infill panels and certain precast concrete suspended floor elements.
Before lifting, a layer of fresh cementitious material is applied along the top concrete surface of foundation footings or previously-installed module walls to act as intermediate padding between the actual steel bearing-plates and shims which comprise the initial contact surfaces. Threaded tie-rods are inserted into all sleeves at the time of lifting and, during the subsequent positioning and lowering operations, they are connected to corresponding threaded couplings which serve as accurate guides atop previously-installed foundations or modules.
Local irregularities in the level of steel bearing-plates can be reduced or eliminated by interposing additional shims of suitable thickness, these being perforated to match the tie-rods as necessary. Tie-rods are tensioned and sleeves grouped, if required, in order to establish continuous vertical connections down through each module to bottom bearing plates, these having similar couplings anchored to the foundations.
Although site-cast reinforced concrete strip footings or pad foundations are generally suitable for low-rise buildings, concrete structures over four stories high maybe best suited to xe2x80x98piledxe2x80x99 foundations irrespective of prevailing soil conditions and site topography. The repetitious layout of modular buildings is particularly suitable for incorporating all the advantages of standardization, speed and versatility of precast concrete foundation elements and their use is preferred with this invention.
Loading from each floor level is considered to be transmitted down through the building via the structural cross-walls of the modules. Piles are to be installed to a common level as pairs, one pile under each end of each crosswall. Piles can either be the cased or uncased xe2x80x98auguredxe2x80x99 type, or be of the xe2x80x98drivenxe2x80x99 precast concrete or pre-formed steel variety.
A pair of piles, each positioned to an accuracy of 3xe2x80x3 (75 mm.) in any direction in plan, is topped-out to a common level by an overlying voided precast concrete capping- beam, spanning between the two piles and enveloping any protruding steel plate connectors or cage reinforcement at the head of the piles, this being temporarily fixed and held in position during the addition of cementitious material which, after setting, serves to fill the voids and Integrate both piles and capping beam. Capping- beams are orientated to the best overall common alignment to suit the cross-walls.
The precast concrete foundation capping-beams have steel plates embedded at their upper surfaces central and adjacent to the projected cross-wall end positions. There are two holes, each offset from the crosswall centre-lines, through which the cementitious material can be introduced and compacted. After piling and capping-beam installation is satisfactorily completed, the steel embedment plates are accurately surveyed for the precise positioning and welding of threaded couplings.
Secondary precast concrete xe2x80x98connecting-beamsxe2x80x99, spanning between the mid-points of capping-beams are designed to prevent any relative movement between the pairs of piles and reinforce the modules under the position of the spine-walls situated centrally between each of the cross-walls. Capping-beams are recessed having a horizontal steel plate embedment to suit the bearing and jointing of xe2x80x98connecting-beamsxe2x80x99 by means of welded connections to matching steel angle embedments at the underside of each end. Longitudinal continuity between pile caps can be improved via steel tendons threaded through central ducts embedded within, and anchored at each end of abutting xe2x80x98connecting beamsxe2x80x99.
Modules are composed of solid, dense reinforced concrete designed in accordance with BS 8110:Part1:1997 cast with fixings, embedments and other sleeves designed to accommodate peripheral and intermediate tendons which are necessary to prevent disproportionate collapse, externally applied insulated render, xe2x80x98in-wallxe2x80x99 heating/cooling pipes and other mechanical and electrical equipment which is to be installed either in the factory or at site.
Suspended concrete floors spanning between module pairs are either made from traditional reinforced concrete cast on site with reinforcement continuity connections embedded within the opposing faces of module floors, or by adapting the module floor edges to accept the well-known xe2x80x98precast beam and blockxe2x80x99 (xe2x80x98double-teexe2x80x99 or similar) method of floor construction.
For the insitu reinforced concrete suspended floor slab application, the formwork edges of inverted xe2x80x98tee-beamxe2x80x99 floors are either cast with female threaded rebar connectors attached, or have reinforcement starter bars simply cast-in at floor edge faces and later exposed and bent out after the erection of modules in order to provide laps for the suspended floor slab reinforcement.
In order to accommodate a xe2x80x98precast beam and blockxe2x80x99 (xe2x80x98double-teexe2x80x99 or similar) floor at each level, manufactured edges of inverted xe2x80x98tee-beamxe2x80x99 module floors are formed with a series of crenellated wedge-shaped pockets into which steel hangers can be fixed in order to provide support for the beam ends. Adjacent hangers can be joined together with welded straps for extra security if required.
For xe2x80x98precast beam and blockxe2x80x99 floors, blocks are installed onto the beam ledges and a sand/cement grout is brushed into the joints.
Peripheral and intermediate tendons are fed through their respective sleeves within the module floors and across the suspended floors prior to a sequence of tensioning and fastening operations. By this means, modules are effectively tied together at the periphery and internally at every floor level.
During the subsequent application of cementitious screed material over each of the suspended floors, the small gaps between the ends of precast beams, blocks, hangers and wedge-shaped pockets are filled and packed with mortar to improve security and protect the otherwise exposed steel hangers and tendons. `Suspended floor xe2x80x98fire ratingxe2x80x99 may be enhanced by the application of an intumescent covering or coating over the otherwise exposed parts of supporting hangers or the provision of a plasterboard ceiling.
External infill walls, comprising insulated panels, doors and window units are craned into position only after suspended floor elements have been fixed at each level, and also prior to the addition of another tier of modules.
Ceilings for the top tier of modules are integrated into the insulated roof assembly, this being fixed by way of structural connection to upper bearing plates.
The completion of thermal insulation, drainage membranes and wearing surfaces applying to module and suspended floor balconies is carried out under-cover once the roof is substantially complete.
All the above in accordance with current Building Regulations and British Standards.